Hungry for more? Check out the new Exploratorium website about the Science of Food.
The Accidental Scientist: Science of Cooking
Candy Bread Eggs Pickles Meat Seasoning
Ask the Inquisitive Cooks    

"What causes the flavor of vegetables to change when cooked?"

Dear Anne and Sue,

What causes the flavor of vegetables to change when cooked? For example, whether I boil, steam, or fry a green bean, the flavor is markedly different from the raw bean. I am assuming that there is a chemical reaction involved. If this is true, what is the reaction? If it is only a physical change, please explain the science involved.
Thank you.

— Dr. Linda B. Knight, Katy, TX


Still have more questions? You'll find more answers in our archived monthly feature articles by the Inquisitive Cooks.

(Meet the Inquisitive Cooks)


Dear Linda,

The flavor of vegetables is comprised of various combinations of acids, sugar, polyphenolic compounds, and volatile oils. Some of these components decompose during cooking and evaporate with the steam that's created during boiling, steaming, and even baking.

Flavor changes are brought about mainly through exposure to heat and water. In the case of beans, the longer they cook, the more flavor they lose—some by evaporation, and some by dissolving in the cooking water.

Just-picked, young green beans may cook in as little as two minutes. Their fragile sweetness is quickly lost as sugar dissolves in water, so however you cook young produce, make it brief and minimize exposure to water to maximize flavor retention. Fatter, older beans with more mature fibers, may take 6 to 8 minutes to cook.

Flavors also vary according to the intensity of the temperature you use in cooking. If you choose to roast or grill those beans, they'll reach much higher temperatures than they do when cooked in water. As they brown, complex reactions create entirely new volatile flavor components that are not present in the raw bean. Thus, roasted vegetables are quite different in both appearance and flavor than the same vegetables cooked by steaming.

Our perception of flavor also includes the dimensions of aroma, texture and color. These too, change according to the cooking method and each change exerts a strong influence on one's perception of flavor.

What takes place in our kitchens is indeed both complex and intriguing.

Anne & Sue


- - - Science of Cooking - - - Webcasts - - - Ask The Inquisitive Cooks - - - Share & Discuss - - -


© Exploratorium | Use Policy | Privacy Policy